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Natural Selection

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Natural Selection. Natural Selection:. A process by which characteristics that make an individual better suited to it\'s environment become more common in the species. Sometimes referred to as “survival of the fittest”. How Does Natural Selection work?.

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Presentation Transcript
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Natural Selection:

  • A process by which characteristics that make an individual better suited to it\'s environment become more common in the species.
  • Sometimes referred to as “survival of the fittest”
how does natural selection work
How Does Natural Selection work?

Those with the unique characteristics best suited for their environment will survive and produce offspring.

End result = ADAPTATIONS

slide4

English Peppered Moth –Natural selection in action

dark moth - random mutation

not as common

Soot covered tree

England 1800’s

camouflaged moth

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Adaptations

  • Behaviors or physical characteristics that allow organisms to live successfully in their environment

Shell for protection

Long neck to reach leaves

Long shallow roots, needles to protect from animals

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Niche

  • An organisms’ role in an ecosystem = niche.
  • Niche and Habitat are different
    • Address of an organism = Habitat
    • “Job” or “Profession” = Niche

Organism = tree

Habitat = Forest

Niche = produce oxygen

provide home for birds

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Explain why two organisms cannot occupy the same niche:

  • If two species occupy the exact same niche in nature, one will die off due to competition for limited resources.
slide8

Video Link – Niche, Competition, Predation, and Symbiosis

http://www.youtube.com/watch?v=D1aRSeT-mQE

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Competition:

  • The struggle between organisms to survive as they attempt to use the same limited resources.
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Predation:

  • An interaction in which one organism kills another for food.
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Predator or Prey:

  • Predator - organism that does the killing
  • Prey – organism that is killed.
slide13

Effect of predation on population size:

  • What variable is plotted on the x-axis? ______
  • What two variables are plotted on the y-axis? ________ and __________

years

# of moose

# of wolves

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Effect of predation on population size:

  • How did the moose population change between 1965 and 1972 ___________
  • How did the wolf population change between 1973 and 1976? __________

It increased

It increased

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Effect of predation on population size:

  • How might the change in moose population have lead to the change in wolf population?
    • The wolf preys on the moose so more moose meant more food for the wolf.
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Effect of predation on population size:

  • How might disease in the wolf population one year affect the moose population the next year?
    • Disease in the wolf population might cause some to die. With less predators, the moose population would most likely increase.
slide17

Examples of Predator Adaptations

  • Cheetah speed
  • Owl eyes
  • Jelly fish venom
slide18

Defense Strategies of Prey

  • Mimicry
  • Protective Covering
  • False Coloring
  • Warning color
  • Camouflage
slide19

Video Link on Predator and Prey Interactions

http://www.youtube.com/watch?v=vZynrBA91fY

slide21

Symbiosis – a close relationship in nature that benefits at least one species

Bacteria from gut of termite

Termites

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Mutualism

  • Both species benefit
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Commensalism

  • One species benefits, but the other isn’t harmed or helped.
slide25

Parasitism

  • One species benefits and the other is harmed.
  • The one benefiting is the parasite
  • The one being harmed is a host
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